ACLS Medication Guidelines: Alteplase Time Frame, Drug Doses & Protocol Mastery

Understanding the alteplase time frame ACLS teams must follow is one of the most high-stakes pieces of knowledge in emergency cardiovascular care. Alteplase, a tissue plasminogen activator (tPA), must be administered within a 3-hour window from symptom onset in most ischemic stroke protocols, and within 4.5 hours for select patients meeting extended criteria. Missing this window not only eliminates a treatment option — it can expose patients to hemorrhagic risk without benefit. Every ACLS-certified provider must be able to recite these time limits under pressure.

ACLS medication guidelines cover far more than alteplase, however. From epinephrine 1 mg IV/IO every 3–5 minutes during cardiac arrest, to amiodarone 300 mg as a first dose for shockable rhythms, each drug in the ACLS algorithm carries a precise dose, route, timing, and indication. These are not suggestions — they are protocols derived from decades of resuscitation science and updated by the American Heart Association (AHA) in alignment with the International Liaison Committee on Resuscitation (ILCOR). Providers who internalize these protocols respond faster and make fewer errors during real emergencies.

Whether you are preparing for your initial ACLS certification or renewing after two years in clinical practice, a firm grasp of pharmacology separates adequate providers from exceptional ones. The ACLS pharmacology component appears directly on certification exams and megacode scenarios alike. Understanding not just the what but the why behind each drug — why you give adenosine 6 mg first and 12 mg second, why dopamine is dosed by weight in mcg/kg/min — helps you adapt when patients don't fit the textbook.

This guide covers the complete ACLS medication list, including first-line cardiac arrest drugs, antiarrhythmics, vasopressors, fibrinolytics, and post-arrest infusions. You will find dose tables, timing protocols, and clinical pearls for each drug class. The article is structured to mirror how you will encounter medications on the ACLS exam: by algorithm, by indication, and by clinical priority. You can use the table of contents to jump directly to the drug class most relevant to your study session.

Preparing for the ACLS exam means more than memorizing a drug list. You need to understand contraindications, recognize when a drug is inappropriate, and know alternative agents. For example, vasopressin 40 units IV was removed from the AHA cardiac arrest algorithm in 2019, but many providers still encounter it in clinical settings and on older study materials. Knowing what has changed — and what has not — is a critical exam skill. Our acls medication guidelines resource gives you the clinical context to make those distinctions confidently.

Practice quizzes are among the most effective ways to lock in pharmacology knowledge. When you answer a question about atropine's role in bradycardia management or the maximum dose of lidocaine as an alternative antiarrhythmic, you are forcing active recall — a learning strategy proven to outperform passive re-reading by a factor of 2 to 3 in retention studies. Throughout this article, you will find links to topic-specific practice tests that mirror real ACLS exam question formats, including drug dosing, algorithm sequencing, and ECG-based pharmacology decisions.

The stakes in ACLS pharmacology are uniquely high. Unlike anatomy questions, a wrong answer on a drug dose question in a real code can directly harm a patient. That is why the AHA has designed ACLS certification to require both written exam performance and practical megacode demonstration. This article gives you the knowledge foundation you need for both. Let's start with the medications you are most likely to encounter first: the cardiac arrest algorithm drugs that every provider must know cold before walking into any resuscitation.

Antiarrhythmic medications in ACLS are organized by the type of abnormal rhythm they target, and understanding this classification is essential for both the written exam and megacode performance. The two most tested scenarios are shockable rhythms requiring amiodarone and supraventricular tachycardia (SVT) requiring adenosine. Each drug has a distinct mechanism, dose, route, and timing requirement that examiners test directly. Mixing up amiodarone and adenosine — two completely different drugs for two different rhythms — is one of the most common ACLS pharmacology errors.

Amiodarone is the first-line antiarrhythmic for ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT) that persists after at least two defibrillation attempts. The initial dose is 300 mg IV/IO as a rapid bolus, followed by a second dose of 150 mg if VF/pVT continues. During the post-arrest period, a maintenance infusion of 1 mg/min for 6 hours, then 0.5 mg/min for 18 hours, is recommended to prevent recurrence. Amiodarone works by blocking sodium, potassium, and calcium channels as well as alpha and beta receptors, which explains its broad antiarrhythmic activity across multiple rhythm types.

Lidocaine 1–1.5 mg/kg IV/IO is the accepted alternative to amiodarone when amiodarone is contraindicated or unavailable. A second dose of 0.5–0.75 mg/kg may be given, with a maximum cumulative dose of 3 mg/kg. Unlike amiodarone, lidocaine lacks the multi-channel effects and has a faster onset with a shorter duration of action. Some providers prefer lidocaine in settings where QT prolongation — a known amiodarone side effect — is a concern, such as in patients already taking other QT-prolonging agents.

Adenosine is the drug of choice for stable narrow-complex tachycardia suspected to be SVT. The dose is 6 mg IV rapid push, followed immediately by a 20 mL normal saline flush, then 12 mg if the first dose is ineffective. A third dose of 12 mg may be given if needed. The half-life of adenosine is less than 10 seconds, which means it must be administered in a large peripheral IV or central line using the most proximal access point available. Slow or distal administration results in drug degradation before it reaches the AV node.

For stable wide-complex tachycardia, the approach changes based on whether the rhythm is regular or irregular. Regular wide-complex tachycardia with a pulse is treated as VT until proven otherwise. Options include amiodarone 150 mg IV over 10 minutes, procainamide 20–50 mg/min IV (avoided if prolonged QT or CHF), or sotalol 100 mg IV over 5 minutes. Irregular wide-complex tachycardia may represent atrial fibrillation with aberrant conduction or pre-excitation (WPW), in which case AV-nodal blocking agents like adenosine, beta-blockers, and calcium channel blockers are contraindicated — they can accelerate conduction through the accessory pathway and precipitate VF.

Atropine 1 mg IV is the first-line drug for symptomatic bradycardia. It can be repeated every 3–5 minutes to a maximum of 3 mg (approximately 0.04 mg/kg). Atropine works by blocking vagal tone at the AV node and SA node, increasing heart rate.

It is most effective in sinus bradycardia and AV block at the level of the AV node (e.g., first-degree or Type I second-degree block). Atropine is generally ineffective in Type II second-degree block or complete heart block below the level of the bundle of His — these patients typically need transcutaneous pacing as a bridge to permanent pacemaker placement.

Calcium channel blockers and beta-blockers are used in ACLS for rate control in atrial fibrillation and flutter when the patient is hemodynamically stable. Diltiazem 15–20 mg IV over 2 minutes is the typical calcium channel blocker choice, with repeat dosing of 20–25 mg after 15 minutes if needed. Metoprolol 5 mg IV every 5 minutes (up to 3 doses) is a common beta-blocker option. Both drug classes must be avoided in patients with decompensated heart failure, significant hypotension, or pre-excitation syndromes. When in doubt, electrical cardioversion is safer than pharmacological rate control in unstable patients.

Vasopressors and inotropes play a critical role in post-cardiac arrest care and in managing hemodynamic instability that precedes or accompanies cardiac arrest. The most commonly tested vasopressors in ACLS are dopamine, norepinephrine, and epinephrine as infusions (distinct from the bolus doses used during arrest). Each agent has a different receptor profile and a different clinical use case, and the exam frequently tests your ability to select the right drug for the right hemodynamic picture.

Dopamine is a catecholamine with dose-dependent receptor activity. At low doses of 2–4 mcg/kg/min, dopamine primarily activates dopaminergic receptors, producing renal and splanchnic vasodilation — an effect once believed to be renoprotective, though modern evidence does not support routine use of low-dose dopamine for kidney protection. At intermediate doses of 5–10 mcg/kg/min, dopamine stimulates beta-1 adrenergic receptors, increasing cardiac contractility and heart rate (positive inotropy and chronotropy). At higher doses above 10 mcg/kg/min, alpha-1 effects dominate, causing vasoconstriction and increased systemic vascular resistance.

Norepinephrine is the preferred vasopressor for most forms of distributive shock, including septic shock and neurogenic shock. It acts primarily on alpha-1 receptors to increase systemic vascular resistance, with modest beta-1 activity that supports cardiac contractility. In post-cardiac arrest care, norepinephrine is frequently used to maintain a mean arterial pressure (MAP) above 65 mmHg, which is the target recommended in most post-resuscitation bundles. Typical infusion rates range from 0.01 to 3 mcg/kg/min, titrated to hemodynamic response. Unlike dopamine, norepinephrine has minimal chronotropic effect, making it preferable in post-arrest patients who are already tachycardic.

Epinephrine as a continuous infusion (as opposed to the 1 mg bolus doses used during cardiac arrest) is reserved for severe anaphylaxis, profound bradycardia refractory to atropine, and cases where both vasopressor and inotropic support are needed simultaneously. Infusion doses typically range from 0.01 to 0.5 mcg/kg/min.

In anaphylaxis, the preferred route remains intramuscular (IM) injection into the anterolateral thigh (0.3–0.5 mg of 1:1,000 solution) for initial management, with IV infusion reserved for refractory cases or anaphylactic cardiac arrest. The distinction between epinephrine concentrations — 1:1,000 for IM use, 1:10,000 for IV bolus during arrest — is a classic ACLS exam question.

Vasopressin (antidiuretic hormone, ADH) was removed from the 2019 AHA cardiac arrest algorithm as a routine drug during resuscitation, largely because evidence showed no survival benefit compared to epinephrine alone. However, vasopressin 20–40 units IV remains in use as a vasopressor infusion for refractory vasodilatory shock, particularly in septic shock patients who are failing norepinephrine. ACLS providers should be aware of this distinction: vasopressin is no longer part of the cardiac arrest drug sequence, but it remains a valid option in the post-arrest and shock management setting.

Dobutamine is the inotrope of choice when the primary problem is reduced cardiac contractility with relatively preserved blood pressure — a profile seen in cardiogenic shock without severe hypotension. Dobutamine acts primarily on beta-1 and beta-2 receptors, increasing cardiac output while causing mild peripheral vasodilation. Typical infusion rates are 2–20 mcg/kg/min. Because dobutamine can cause hypotension through its vasodilatory effect, it is often combined with a vasopressor like norepinephrine in patients with concurrent cardiogenic and distributive shock. The ACLS exam may ask you to distinguish the appropriate use of dobutamine versus dopamine in different hemodynamic states.

Magnesium sulfate 1–2 g IV over 15 minutes is the treatment of choice for torsades de pointes (TdP), a polymorphic VT associated with a prolonged QT interval. It is also used for hypomagnesemia-related arrhythmias. Magnesium does not reliably terminate TdP — it primarily prevents recurrence and stabilizes the myocardium while the underlying QT prolongation resolves.

If the patient is hemodynamically unstable, unsynchronized cardioversion is required first, followed by magnesium administration. Remember that the dose for TdP (1–2 g) is different from the obstetric dose used for eclampsia (4–6 g loading dose), a distinction the exam occasionally exploits with clinical vignette framing.

Preparing for the ACLS written exam requires a strategic approach to drug memorization that goes beyond flashcards. The exam tests clinical application — not just what a drug is, but when to use it, when not to use it, and what to do when it fails. One of the most reliable study strategies is to organize medications by algorithm rather than by drug class. When you learn that the cardiac arrest algorithm always starts with CPR, then rhythm check, then epinephrine or defibrillation, the drugs become attached to a sequence rather than floating in isolation in your memory.

Understanding the relationship between ECG rhythms and drug choices is another high-yield exam skill. The four rhythms that can cause pulseless cardiac arrest — ventricular fibrillation (VF), pulseless ventricular tachycardia (pVT), pulseless electrical activity (PEA), and asystole — each have a distinct treatment pathway. VF and pVT are shockable and receive amiodarone after the third shock. PEA and asystole are non-shockable and receive epinephrine immediately. The ability to look at an ECG strip, identify the rhythm, and select the correct drug without hesitation is exactly what the megacode station tests.

A practical drill that many successful ACLS candidates use is the drug-dose-route-timing matrix. For each ACLS medication, write down four columns: drug name, dose, route, and timing/frequency. Practice filling in the matrix from memory, then check your answers. Over several sessions, add a fifth column for contraindications. This approach ensures you do not know the dose but forget the contraindication — which is the exact trap the exam sets when it gives you a patient with WPW and asks which rate-control drug to choose.

Time-sensitive protocols like the alteplase time frame ACLS teams follow deserve special attention because they are testable in multiple question formats. You might be asked directly: what is the window for alteplase in ischemic stroke? Or the question might be scenario-based: a patient presents 5 hours after last known well with acute stroke symptoms and no contraindications. Is alteplase indicated? The answer depends on whether the patient meets extended window criteria. Knowing the 3-hour standard window and the 4.5-hour extended criteria cold allows you to answer both question formats correctly.

Drug calculation practice is an area many candidates underestimate. The ACLS exam may include questions where you must calculate an infusion rate from a weight-based dose order. For example: a 70 kg patient requires a dopamine infusion at 5 mcg/kg/min. The standard dopamine preparation is 400 mg in 250 mL D5W (1,600 mcg/mL). What is the infusion rate in mL/hour? Working through these calculations before the exam prevents the math from becoming a source of panic. The formula is: (dose in mcg/kg/min × weight in kg × 60 min/hr) ÷ concentration in mcg/mL.

Practice tests are one of the single most valuable tools available to ACLS candidates, and using them strategically maximizes their benefit. Rather than taking a full practice test and reviewing only your wrong answers, try categorizing errors by drug class or algorithm. If you consistently miss questions about adenosine administration technique, that signals a targeted review opportunity — not a general pharmacology weakness. By linking your practice test performance to specific knowledge gaps, you can allocate study time efficiently rather than re-reading content you already know well.

The ACLS exam also includes scenarios involving special populations where standard drug protocols may be modified. Pediatric patients require weight-based dosing for all medications — epinephrine in pediatric cardiac arrest is 0.01 mg/kg IV/IO (1:10,000 concentration). Pregnant patients in cardiac arrest require manual left uterine displacement to relieve aortocaval compression while CPR is performed. Hypothermic cardiac arrest patients may not respond to medications at core temperatures below 30°C, and drug intervals may be doubled between 30°C and 35°C. These nuances appear less frequently than standard adult protocols but are tested precisely because they are easy to overlook under exam pressure.

Practical exam success in ACLS pharmacology comes down to a handful of habits built before you walk into the testing room. The first is daily active recall. Instead of reading your drug list every day, close the book and write it from scratch. Start with cardiac arrest drugs (epinephrine, amiodarone, lidocaine), then move to rhythm-specific drugs (adenosine, atropine, diltiazem), then fibrinolytics (alteplase), then vasopressors (dopamine, norepinephrine, dobutamine). The act of retrieval — even when you get it wrong — strengthens memory more than re-reading the correct answer.

The second habit is practicing with scenario-based questions every study session. Single-fact recall is necessary but not sufficient. The ACLS exam presents patients, not drug names. A question that says a 58-year-old male in cardiac arrest has been in VF for 8 minutes, has received two shocks and one round of CPR, and now has IV access established — what do you give next? You need to know the algorithm well enough to answer that without counting on recognition-based clues. That means practicing with scenario questions, not just definition questions.

Third, build a personal drug error list. Every time you miss a pharmacology question, add it to a running list with a short note about why you got it wrong. Did you confuse the dose? Did you pick the wrong drug for the rhythm? Did you forget a contraindication? Reviewing this list the night before your exam is more efficient than a full content review because it targets your specific gaps rather than the entire pharmacology curriculum.

Fourth, use the full alteplase checklist as a study anchor. Because alteplase has multiple time windows, multiple contraindications, and multiple indications (stroke, PE, cardiac arrest with suspected PE), it is one of the richest single-drug topics on the ACLS exam. If you can talk through the complete alteplase protocol for each indication from memory — dose, timing, contraindications, BP requirements, and monitoring — you have demonstrated a level of pharmacology integration that will carry you through nearly any fibrinolytic question on the exam.

Fifth, know the drugs that have been removed or downgraded in recent AHA updates. Vasopressin as a first-line cardiac arrest drug (removed 2019), routine sodium bicarbonate in cardiac arrest (not recommended without specific indications like hyperkalemia or TCA overdose), and calcium chloride as a routine ACLS drug (reserved for hyperkalemia, hypermagnesemia, hypocalcemia, and CCB toxicity) are all former ACLS staples that still appear in outdated study materials. Being able to identify outdated protocols is itself a tested skill in some ACLS programs.

Sixth, simulate the megacode pharmacology component during your preparation. In the megacode, you will be the team leader or a team member executing drug orders under time pressure. Practice saying drug orders out loud: dose, route, concentration, and expected flush. Practice closed-loop communication: hear the order repeated back, confirm, and watch for execution. The cognitive load of team leadership during a code is far higher than answering a written question, and pharmacology errors under pressure are much more likely if you have only studied drugs as isolated facts rather than as part of a lived, practiced protocol sequence.

Finally, use every resource available — video reviews, algorithm posters, drug cards — but always return to active practice as your primary preparation method. Passive review is comfortable but produces inferior retention. Every 30 minutes of practice testing will do more for your ACLS medication knowledge than 90 minutes of passive reading.

Build your study schedule around this principle: read once for comprehension, then practice repeatedly for retention. Arrive at your ACLS certification exam with the drugs not just memorized, but automated — so deeply known that your conscious mind is free to focus on the patient, the team, and the algorithm rather than searching your memory for a dose you should have already locked in.